What do you get when you cross fungus with algae? LICHENS!

Well, lichens are not creatures, per se, but they are certainly unusual organisms. Unlike mosses or liverworts, lichens are not true plants.
They are not a single organism like other living things but a combination of two organisms living symbiotically together. Most of the lichen is
composed of fungal filaments living among alga cells, usually green algae or cyanobacterium (previously called blue-green algae). Since fungi
does not contain chlorophyll or have any other means of producing their own food, they rely on other organisms, such as algae, for nutrition.
The algae uses sunlight to make sugars (food) that feed both the fungus and the algae. The fungus then creates a distinctive lichen body
called a thallus that houses both organisms. Each fungi-algae combination creates a unique thallus that is identifiable from others.

There are approximately 3,600 known
species of lichen in North America!
Approximately a quarter of all known
fungi world-wide are “lichenized”. Most
lichens appear different from other fungi,
like mushrooms, and have a texture that is
usually more fibrous and stiff, compared
to non-lichenized fungi, which are usually
soft, fleshy and delicate to the touch. Also
non-lichenized fungi lack algae and do not
appear green in color.

Why are lichens so important
to life? Lichens are ecologically
important as they convert carbon
dioxide in the atmosphere through
photosynthesis into oxygen. They
provide an important role in survival
in harsh environments, as food and
shelter. Many birds and small mammals,
such as squirrels, use lichen for shelter
and nesting material. They are also an
essential winter food for many ungulates
such as black tail deer, mountain goats
and caribou, making up 90% of caribou’s
winter diet. Other uses for lichens are as
a human food source (beware some are
poisonous), manufacturing of antibiotics
and for dying wool. Lichens are very slow
growing and many do not recover well
from collecting or disturbance.

Lichens have evolved to live in a
variety of climates and ecosystems, and
have the ability to absorb everything in
their atmosphere, especially pollutants.
Pollutants such as heavy metals, nitric
and sulfuric acids (acid rain) and
carbon are absorbed into the thallus of
the lichen. Toxins can be extracted to
determine the levels of pollutants that
are present in our atmosphere. When
there is an excess of pollutants in the air,
lichens are unable to survive. Utilizing
this sensitivity to air quality makes
them a dependable air quality indicator
species. Throughout the world, lichens
are being used to detect specific air
quality changes, monitor for pollutants
and track climatic changes. Scientists
use this information to evaluate air
quality and climatic trends and to assess
ecological impacts to our air.